I have configured mirroring with high safety without automatic failover mode. For testing purpose I want to failover between Principal and Mirror. Say, Principal server gets down. Now I want to switch role of Mirror to Principal. But how? Please let me know.

Imagine, Mirror is now Principal and former Principal Server is live again. At this time I want that former Principal takes the role of Principal and start functioning. But how? please let me know.

Actually my Principal server got down. It will take some hours to be ok. That's why I have to use Mirror database to run my application. In Mirror database it is stated as myDB (Mirror, Disconnected/ In Recovery). But I configured mirroring with high safety without automatic failover mode. So I have to make Mirror as Principal. But how?